Removable Partial DenturesIntroduction and Basic Principles

Removable Partial Dentures – Introduction and basic components of RPD’s — Course Transcript

• 1. The UCLA – RPI System per Kratochvil Contributors John Beumer III, DDS, MS Ting Ling Chang, DDS Aria Davodi, DDS Tak Ogawa DDS, PhD Michael Hamada, DDS George Perri DDS Eugene King, DDS
• 2. Introduction and Basic Principles Ting Ling Chang and John Beumer III Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry UCLA School of Dentistry This program of instruction is protected by copyright ©. No portion of this program of instruction may be reproduced, recorded or transferred by any means electronic, digital, photographic, mechanical etc., or by any information storage or retrieval system, without prior permission.
• 3. The Partially Edentulous Patient A turning point in the life of the dentition Multiple missing teeth Teeth may move out of arch symmetry because of loss of adjacent teeth or space irregularities Courtesy T. Berg
• 4. The Partially Edentulous Patient A turning point in the life of the dentition When teeth lack mesial or distal contacts the arch is unable to function as a unit Loss of this arch integrity is the first step in a cycle that leads to arch disorganization and, continued loss of teeth and eventually edentulism
• 5. The Ucla philosphy of RPD design (The RPI system per Professor FJ Kratochvil) 1 st priority The prosthesis must be designed and function in a way to preserve the health and integrity of the remaining dentition and edentulous soft tissue bearing surfaces . The principle focus of the design philosophy is on extension based removable partial dentures If these cases are improperly designed, the prosthesis will damage the remaining teeth and soft tissues.
• 6. A typical partially edentulous patient Missing posterior occlusion Moderate wear and reduced vertical dimension of occlusion Numerous spaces between the teeth Unfavorable tooth contours for RPD support and retention
• 7. A typical partially edentulous patient Missing posterior occlusion Moderate wear and reduced vertical dimension of occlusion Numerous spaces between the teeth Unfavorable tooth contours for RPD support and retention
• 8. A typical partially edentulous patient Missing posterior occlusion Moderate wear and reduced vertical dimension of occlusion Numerous spaces between the teeth Unfavorable tooth contours for RPD support and retention
• 9. A typical partially edentulous patient Missing posterior occlusion Moderate wear and reduced vertical dimension of occlusion Numerous spaces between the teeth Unfavorable tooth contours for RPD support and retention
• 10. The Partially Edentulous Patient Natural progression of a dental arch in this condition Loss of stability of individual teeth Movement and tipping of teeth Altered occlusal relationships and the plane of occlusion Loss of vertical dimension Unfavorable leverage forces on the individual teeth leading to further compromise of the periodontium
• 11. The Partially Edentulous Patient Natural progression of a dental arch in this condition Loss of stability of individual teeth Movement and tipping of teeth Altered occlusal relationships and the plane of occlusion Loss of vertical dimension Unfavorable leverage forces on the individual teeth leading to further compromise of the periodontium
• 12. A typical partially edentulous patient – Goals Replace missing posterior occlusion Improve esthetics and function Restore arch integrity and provide proper stability (bracing), support and retention for the RPD
• 13. A typical partially edentulous patient Replace missing posterior occlusion Improve esthetics and function Provide proper stability (bracing), support and retention for the RPD The prosthesis must be designed and function in a way to preserve the health and integrity of the remaining dentition and edentulous soft tissue bearing surfaces.
• 14. Objectives of treatment of the partially edentulous Reorganize, stabilize and restore the integrity of the dental arches. Restore tooth to tooth contacts (mesial-distal) Restore the plane of occlusion Restore the vertical dimension of occlusion Restore a biomechanically harmonious occlusion
• 15. Objectives of treatment of the partially edentulous Reorganize, stabilize and restore the integrity of the dental arches. Methods to accomplish these objectives: Orthodontic therapy to reposition teeth Preprosthetic surgery Periodontal therapy Conventional restorative procedures and fixed partial dentures Removable partial dentures
• 16. Methods to accomplish these objectives: Orthodontic therapy to reposition teeth Pre prosthetic surgery
• 17. Methods to accomplish these objectives: Pre prosthetic surgery Orthognathic surgery to reposition posterior maxillary segment superiorly
• 18. Methods to accomplish these objectives: Pre prosthetic surgery Removal of unwanted tori
• 19. Methods to accomplish these objectives: Periodontal therapy Abutments adjacent to extension bases with compromised periodontal support may require special consideration: Splinting of abutments when crown root ratios become unfavorable Stabilization of multiple abutments with RPD framework Attention to occlusion: Anterior guidance with centric only contact in the extension base region.
• 20. Methods to accomplish these objectives : Periodontal therapy Abutments adjacent to extension bases with compromised periodontal support may require special consideration: Splinting of abutments when crown root ratios become unfavorable Stabilization of multiple abutments with RPD framework Attention to occlusion: Anterior guidance with centric only contact in the extension base region.
• 21. Methods to accomplish these objectives: Periodontal therapy Abutments adjacent to extension bases with compromised periodontal support may require special consideration: Splinting of abutments when crown root ratios become unfavorable Stabilization of multiple abutments with RPD framework Attention to occlusion: Anterior guidance with centric only contact in the extension base region.
• 22. Methods to accomplish these objectives: Periodontal therapy Abutments adjacent to extension bases with compromised periodontal support may require special consideration Widening the zone of attached gingiva
• 23. Methods to accomplish these objectives: Fixed partial dentures and individual restorations Diastemas have been closed Missing space filled Arch integrity has been restored Courtesy Dr. A. Davodi
• 24. Methods to accomplish these objectives Arch integrity has been restored In this case with a proximal plate between the cuspid and premolar (arrow)
• 25. Methods to accomplish these objectives Arch integrity has been restored with the rests and proximal plates of the RPD framework in a periodontally impaired residual dentition
• 26. Methods to accomplish these objectives What is the role of endodontics?? Endodontically treated teeth with compromised periodontal support adjacent to extension bases may be poor candidates for RPD abutments Higher susceptibility to fracture Higher stress levels within the root Avoid occlusal rests on these teeth if possible
• 27. Methods to accomplish these objectives What is the role of endodontics?? Endodontically treated teeth with compromised periodontal support adjacent to extension bases may be poor candidates for RPD abutments Higher susceptibility to fracture Higher stress levels within the root Avoid occlusal rests on these teeth if possible Tooth # 12 was treated endodontically. Note the absence of a rest (arrow).
• 28. Methods to accomplish these objectives What is the role of endodontics?? To resolve occlusal plane problems To retain teeth To retain teeth as overdenture abutments
• 29. Methods to accomplish these objectives What is the role of endodontics?? As overdenture abutments
• 30. Methods to accomplish these objectives Individual restorations Recontouring the occlusal surface
• 31. Methods to accomplish these objectives Individual restorations
• 32. Current Concepts of Removable Partial Denture Design Why is it so important to be familiar with the basic principles required to fabricate removable partial dentures Because this will be the primary method used to restore missing dentition and arch integrity for the foreseeable future
• 33. The Future of RPD’s is Bright! Aging population Fixed is not possible in many partially edentulous patients Osseointegrated implants are costly and as a result this service will be available to very few individuals Very significant need
• 34. RPD Indications Long edentulous spans Structurally and anatomically compromised abutments Absence of adequate periodontal support Need for cross-arch stabilization
• 35. RPD Indications Long edentulous spans Structurally and anatomically compromised abutments Absence of adequate periodontal support Need for cross-arch stabilization
• 36. RPD Indications Distal or anterior extension Need to restore soft and hard tissue contours Anterior esthetics
• 37. RPD Indications Age and health Attitude and desires of pt. Cost of implants and fixed Ease of plaque removal
• 38. Removable Partial Dentures Tooth loss is creating more partially edentulous patients In many patients fixed partial dentures are not indicated Cost of implants precludes this therapy for most patients Tooth loss patterns – A significant number of patients need extension base RPD’s Most commonly retained teeth #22-27
• 39. What about implants? RPD’s will be needed in the future Numbers of patients continues to expand Unmet needs continue to increase Implants will not replace RPD’s 40 patients considered implant fixed partial dentures Barriers to receiving implants Economic concerns Poor patient compliance Patient satisfied with the RPD Fearful or skeptical of the result One patient received implants out of the 40 originally screened (Bassi et al, 1996) Probably less than 3% of all partially edentulous patients in the United States will be restored with implant therapy
• 40. RPD’s and compromise of the remaining dentition RPD’s and oral health Perceived compromise of the remaining teeth by the RPD is not supported by the evidence No evidence of destruction of the periodontium of remaining teeth Most important factors are patient compliance and close followup
• 41. RPD’s and compromise of the remaining dentition Causation or association Some have maintained that the presence of an RPD accelerates existing dental disease However, the risk is reduced with appropriate followup and oral compliance Poor outcomes in some studies may be related to the fact this patient group may have low dental IQ
• 42. Patient Satisfaction – RPD’s Patient satisfaction Review of 400 mandibular RPD’s provided by private dentists Results 74% satisfied with their RPD’s 26% dissatisfied with their RPD’s (Frank et al, 1998) This a remarkable finding particularly when you consider that most RPD’s are improperly designed and fabricated.
• 43. RPD Quality Control Design standards Less than 5% of casts submitted to dental labs have designs Less than 5% of casts submitted to dental labs have definable rests In many studies significant numbers of RPD’s do not meet even half of the usual customary design standards In one recent study, only 1/3 of the RPD’s were judged to be adequate
• 44. Prosthodontic Education Most dentists are poorly trained in RPD design In some dental schools as many as a quarter of graduates have never made either a RPD, a complete denture or a fixed bridge Only 14% of US dental schools offer clinical experience in restoring dental implants* * ADEA Implant Workshop Survery, 2004
• 45. Why consider RPD’s Clinical trials – Fixed vs Removable 5 year followup Removable vs fixed outcomes in Class I and Class II patients RPD’s vs tooth and implant supported FPD’s Results No periodontal differences at 5 years Maintenance needs for RPD’s is greater Kapur et al, 1989 Budtz-Jorgenson et al, 1990
• 46. RPD’s vs Implants Mastication efficiency A r andomized clinical trial comparing Fixed implant-supported and removable partial dentures Kapur et, al,1993
• 47. Conclusions Kapur et, al,1993 Both RPD and FPD treatments were successful in approximately 80% of the patients over 5 years. Both treatments were equally effective in improving chewing function . A large number of patients in both groups expressed satisfaction with the prosthesis. Improvement with FPD was more frequent than with RPD for several perceptions. Despite the slight superiority of the FPD in terms of patient satisfaction, lack of functional differences and success rates do not support the selection of implant-supported FPD over RPD, without consideration of other factors.
• 48. Limiting factors for placement of implants Posterior maxilla and mandible Pneumatized sinus Presence of inferior alveolar nerve
• 49. Sinus Lift and Graft This procedure has shown good predictability
• 50. Sinus Lift and Graft This patient was restored following a sinus lift and graft. Autogenous chin bone was used. She is 10 years post treatment and doing well. Success rates over 85% at 5 year followup Problem: Cost $3-5000 per sinus in the US
• 51. Distraction Osteogenesis This procedure has been used successfully. Its usefulness in the posterior maxilla is probably limited. Even if successful onlay grafts to widen the site are almost always necessary 25% relapse rate Slide courtesy Dr. R. Nishimura
• 52. *Removable Partial Dentures* Removable partial dentures provide the patient with masticatory function equivalent to that obtained with an implant supported fixed partial denture and this service should be offered to the patient before grafting is considered.
• 53. Posterior Mandible – Limiting Factors Inferior alveolar nerve (arrow) Insufficient bone over the nerve to permit placement of an implant of suitable length
• 54. Many patients such as this one, present with moderate to severe resorption precluding placement of implants unless the inferior alveolar nerve displaced. Posterior Mandible – Limiting Factors
• 55. Displacement of the Inferior Alveolar Nerve This procedure enables placement of implants of sufficient length with bicortical anchorage. The morbidities associated with injury may be severe. Therefore, these issues must be thoroughly discussed with the patient before proceeding with the procedure.
• 56. Bone Augmentation Augmentation of vertical defects in posterior quadrants with free autogenous bone grafts has been unpredictable. Average gain is only about 2-3 mm. Such grafts are subject to resorption particularly upon occlusal loading (relapse rate is 75%). Initial anchorage may be more difficult to achieve B A
• 57. Use of Short Wide Diameter Implants in the Posterior Mandible Length is more important than width. Short wide diameter implants appear to be susceptible to overload when used in linear configurations such as shown here. 2 years 5 years
• 58. *Removable Partial Dentures* Removable partial dentures provide the patient with masticatory function equivalent to that obtained with an implant supported fixed partial dentures and this should treatment be offered to the patient before grafting is considered. Courtesy Dr. A. Davodi
• 59. The Basic Principles of Removable Prosthodontics Support Stability (bracing ) Retention Our goal is to provide these phenomenon for our removable partial dentures within the physiologic limits of the remaining dentition and edentulous mucosal bearing surfaces.
• 60. Principles of RPD design Occlusal rests must direct occlusal forces along the long axis of the teeth. Extension base RPD designs must anticipate and accommodate the movements of the prosthesis during function, without exerting pathologic stresses on the abutment teeth Major connectors must be rigid. Guide planes are employed to enhance stability and bracing. Retention must be within the limits of physiologic tolerance of the periodontal ligament. Maximum support is gained from the adjacent soft tissue denture bearing surfaces. Designs must consider the needs of cleansibility.
• 61. Components of a Removable Partial Dentures Positive Rests Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth
• 62. Components of a Removable Partial Dentures Rests Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth A rigid extension of a partial denture which contacts a remaining tooth in a prepared rest seat to transmit vertical or horizontal forces .
• 63. Components of a Removable Partial Dentures Rests Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth Function: Provide support and on occasion stability (bracing) Controls the position of the prosthesis in relation to the teeth and soft tissue supporting structures
• 64. Components of a Removable Partial Dentures Rests Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth That component of a removable partial denture used to prevent dislodgement, consisting of a clasp assembly or precision attachment
• 65. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth Function: Provide retention and stability (bracing) Control the position of the prosthesis in relation to the remaining teeth and supporting structures
• 66. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth That part of a removable partial denture that joins the components on one side of the arch to those on the opposite side.
• 67. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth Function: Provide support Unite and stabilize the remaining teeth in the arch
• 68. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth The connecting link between the major connector or base of the removable partial denture and the other units of the prosthesis, such as the clasp assembly, indirect retainers, occlusal rests, or cingulum rests
• 69. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth Function: Provide stability (bracing)
• 70. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Proximal plate Denture base connector Denture base Teeth A plate of metal in contact with the proximal surface of an abutment tooth
• 71. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Rest Proximal plate Denture base connector Denture base Teeth Function: Provide stability by anterior posterior bracing action Retention
• 72. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Rest Proximal plate Denture base connector Denture base Teeth That part of the framework to which the resin denture base is connected
• 73. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Rest Proximal plate Denture base connector Denture base Teeth Function: Retain denture base
• 74. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Rest Proximal plate Denture base connector Denture base Teeth That part of denture that rests on the foundation tissues and to which the teeth are attached
• 75. Components of a Removable Partial Dentures Rest Direct retainers Major connector Minor connector Rest Proximal plate Denture base connector Denture base Teeth
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